Field of the Invention
The present invention relates to a battery for an electric vehicle, and more particularly to a method and apparatus for controlling recharging of an auxiliary battery for an electric vehicle.
Discussion of the Related Art
Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), which are equipped with a recharging system, are provided with two batteries, namely, a main battery configured to supply drive power to an electric motor to drive wheels, and an auxiliary battery configured to supply electric power to general electric elements.
In other words, such an EV requires an operating voltage to start or initiate electric elements, and a drive voltage to drive a motor for movement of the EV. The operating voltage and drive voltage are supplied to the batteries. Generally, for supply of the drive voltage, a high-voltage battery (or a main battery), which has relatively high energy density and relatively high output density, is used. However, electric elements of the EV operate at several volts and, thus, are configured to receive a desired voltage from a separate electric-element battery (or an auxiliary battery), which is adapted to supply a voltage suitable for the electric elements.
However, the auxiliary battery may be discharged after engine turn-off, in spite of the presence of the main battery for driving of the vehicle. Furthermore, once the auxiliary battery is discharged to a final discharge voltage, the auxiliary battery may no longer be used and, thus, re-operation of the vehicle may be impossible.
Accordingly, to solve the problems caused by discharge of the auxiliary battery, various methods have been developed in the related art. For example, a method has been developed in which voltage supply from an auxiliary battery is automatically cut off when a predetermined condition is satisfied (e.g., when door locking is performed after engine turn-off under the condition that headlights are in an ON state), voltage supply from an auxiliary battery is automatically cut off, or the headlights are automatically turned off, and a method in which, when a predetermined time elapses after turn-on of vehicle accessories (ACCs), voltage supply from an auxiliary battery is automatically cut off. In such methods of the related art, however, there is a limitation in solving discharge of the auxiliary battery caused by dark current. Therefore, it is necessary to provide a recharging control technology capable of maintaining the auxiliary battery at least in a rechargeable state.